Regulation of human type II phosphatidylinositol kinase activity by epidermal growth factor-dependent phosphorylation and receptor association.

摘要: Epidermal growth factor (EGF) stimulates phosphatidylinositol PtdIns) hydrolysis in many cell types by effecting the specific interaction between EGF receptor and phospholipase C gamma. Several studies have suggested that PtdIns 4-kinase activity can also be regulated EGF, but mechanism of this stimulation was unclear. We report here treatment intact A431 cells increased association type II kinase with within 1 min at 37 degrees C. Phosphorylation immunoprecipitated 4-kinase. Furthermore dephosphorylation phosphoserine residues on stimulated immune complex led to inactivation bound 4-kinase, while phosphotyrosine activation. Unlike measured total plasma membrane lysates, changes immunoprecipitates were apparent high substrate concentration. Metabolic labeling used show a 55-kDa phosphotyrosine-containing protein comigrated renatured SDS-polyacrylamide gel electrophoresis, vitro revealed only serine phosphorylation. These data are discussed reference direct regulation phosphorylation, compartmentalization, formation multienzyme signal transduction complex.